Abstract
BACKGROUND: The gut barrier is essential for animal health as it prevents the passage of potentially harmful foreign substances. The epithelial tight junctions support the intestinal barrier and can be disrupted by stress caused, for example, by pathogens or dietary or environmental factors, predisposing the host to disease. In animal husbandry, phytogenics (plant-derived feed additives) are used to support and maintain growth, feed efficiency and health. Therefore, several phytogenics were tested in vitro for their influence on the barrier function recovery of intestinal porcine epithelial cells (IPEC-J2) after disruption, particularly on the abundance of tight junction proteins. RESULTS: IPEC-J2 treated with 1,000 µg/ml liquorice root extract, 80 µg/ml plant powder mix, or 80 µg/ml angelica root powder showed significantly higher trans-epithelial electric resistance (TEER) 24 hr after tight junction disruption via a calcium switch assay than the control. In contrast, cells treated with 1,000 µg/ml oak bark extract showed a significantly lower TEER after 6 hr but not at later time points. The increased TEER caused by the liquorice root extract correlated with an increase in the abundance of the tight junction protein claudin-4. CONCLUSIONS: This study suggests potential beneficial effects of liquorice and angelica root extracts on the gut barrier function when used as feed additives for livestock. Further studies, especially in vivo, are necessary to confirm these findings.